Study On Integration Of Microseismic Events And Production Modeling In Volume Fractured Shale Reservoir

The practice of exploration and development of shale reservoir shows that horizontal well drilling and volume fracturing are the key technologies to realize commercial development of shale reservoir,and microseismic data are the key parameters to evaluate the volume of reservoir stimulation.On the one hand,the direct monitoring methods,such as microseismic monitoring and inclinometer,are difficult to be applied on a large scale because of their specific engineering operation conditions,interpretation accuracy and economic cost constraints.On the other hand,the numerical simulation method of microseismic event prediction lacks certain scientificity,which separates the evaluation of stimulated reservoir volume from the prediction of production performance after fracturing,and limits the application potential of microseismic data.In this paper,the triggering mechanism of microseismic events during hydraulic fracturing and the complex flow behavior of gas in stimulated shale reservoirs are investigated systematically.A mathematical model for predicting microseismic events and production performance of fractured shale reservoirs is established.The main contents are as follows:(1)The mathematical model for predicting micro-seismic events of shale reservoir volume fracturing was studied.The random natural fractures developed in shale reservoirs are considered as conjugate fracture systems.Based on rock mechanics and seepage mechanics,triggering criteria of micro-seismic events are derived.The mathematical model for predicting micro-seismic events in volume fracturing of shale reservoirs is established by combining hydraulic fracture extension equation,fracturing fluid filtration equation,fracturing fluid flow equation and permeability equation.(2)Microseismic event prediction and sensitivity analysis.Based on the established mathematical model for predicting micro-seismic events in shale reservoir volume fracturing,the triggering and evolution behavior of micro-seismic events are described in detail.The main geological parameters and engineering parameters affecting the distribution of micro-seismic events are sensitively analyzed,and the reliability of the model is verified by using the actual in-situ micro-seismic monitoring data.(3)The mathematical model of production dynamic simulation of volume fracturing production in shale reservoir is studied.Within the distribution range of predicted microseismic events,the fractured area is considered as porous medium,the multi-scale flow behavior from organic micro to inorganic macro and the stress sensitive effect in production process are considered,and the production dynamic simulation mathematical model of"organic-inorganic-fracture system" triple medium is established.(4)Integrated prediction of microseismic events and production performance of volume fractured shale reservoirs.The increment of reservoir permeability in the prediction range of microseismic events is transferred to the mathematical model of production dynamic simulation,and the integration calculation of microseismic events and production prediction is preliminarily realized based on field production data fitting verification.The influence of geological and engineering parameters on post-fracturing productivity prediction is quantitatively analyzed to guide pre-fracturing optimization design and post-fracturing evaluation.